[amsat-bb] Sunday afternoon AMSAT demonstration in Phoenix, including new satellites!

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb at wd9ewk.net
Mon Oct 12 05:53:36 UTC 2015


I received an e-mail asking about a demonstration of satellite operating,
possibly this afternoon if I had the time. It is still warm here in the
Phoenix area, but not over 100F/38C today, so I went to a city park in the
southeast corner of Phoenix in grid DM43ah. I was out here a couple of
months ago, and this time the plan was to try focusing on the satellites
from AMSAT and China that had been recently launched. I worked SO-50,
FO-29, the ISS, XW-2E, and AO-85 from the park. While working AO-85,
XW-2F was passing by at the same time. I was able to hear both of these
satellites, as I focused on working AO-85.

The demonstration started in the mid-afternoon, with an SO-50 pass just
after 2pm/2100 UTC. I did a simple demonstration, using my Kenwood TH-D72A
HT and Elk log periodic, working a few stations. Around 2140 UTC, there
was a very nice FO-29 pass, and I worked it using one of my FT-817NDs and
the Elk log periodic. This was only the second time I tried working FO-29
half-duplex, and I was able to chat with Tom WA0POD for a couple of minutes
for my only QSO on that satellite.

The ISS passed by around 2200 UTC, and I was unsuccessful in sending my
packets through the digipeater. When I got home tonight, I think I figured
out the issue - wrong packet path on 145.825 MHz. Oops. We heard a bit of
activity from around the western USA, including KG7NXH (not far to the
east of this park, in another Phoenix-area suburb). Then a break for lunch,
and talking about the new satellites and other topics like using SDR
receivers, before the fun really started...

For passes of XW-2E, XW-2F, and AO-85 around 0100 UTC, I went back to that
city park and set up a couple of stations. One I used for my operating:

Yaesu FT-817ND for SSB transmit
Icom IC-2820H for FM transmit
SDRplay SDR receiver
8-inch HP Windows 10 tablet with HDSDR (making RF recordings of the passes)
Elk 2m/70cm log periodic antenna

and another station for receiving:

FUNcube Dongle Pro+
10-inch Winbook Windows 10 tablet with HDSDR
AMSAT-UK (Winkler) VHF crossed dipole

XW-2E came first. I heard a couple of stations on, tried to get a clear
spot to call CQ, and ended up making 4 QSOs while keeping an eye on the
clock. I saw that XW-2F and AO-85 were passing by our location around the
same time. I had worked XW-2E in SSB, so I suggested I try AO-85 in FM.
This was an interesting experience...

For the first few minutes of the pass, I saw - and occasionally heard -
the XW-2F CW beacon that was just below the AO-85 FM/data downlink. I was
using narrow FM, about 14 kHz in HDSDR, and I raised the audio filter for
the low side of the audio passband to eliminate any part of the slow-speed
data from reaching my ears. Did I mention I am really enjoying SDR for my
satellite work? :-) This is something that made the audio more pleasing to
hear. Not stereo quality, of course, but no buzzing from remnants of the
telemetry making it into the audio we hear on our radios when working the
FM repeater.

About 10 kHz or so above the AO-85 downlink, I saw an SSB signal pop up in
the XW-2F transponder. When I played the HDSDR RF recording back at home, I
found it was Leo W7JPI calling CQ on the XW-2F transponder. Not much on
that transponder, but a larger crowd on AO-85. I was able to make 5 QSOs on
AO-85, and - later - upload some data to the AMSAT server.

The second station had some issues I will need to investigate, especially
with the XW-2E pass. It is possible I should have brought out my second Elk
log periodic, instead of relying on the crossed dipole. Even with the
receive issues at the second station, it was still a good illustration of
using SDR receivers for satellite work, and showing that the inexpensive
Windows tablets are capable of running HDSDR and the Fox telemetry software

As I write this e-mail, my uploads to Dropbox have completed. I put the RF
recordings from the XW-2E and AO-85/XW-2F passes, along with some photos of
my setup for the later passes and other screengrabs in separate folders
there. You can go to http://dropbox.wd9ewk.net/ (hit F5 a few times, if the
folder/file listing doesn't immediately show in your browser) to see those
files. I didn't make a separate MP3 recording of the AO-85 pass, relying on
the RF recording for my logging when I returned home this evening.

I really don't have many new observations for AO-85 tonight. I worked it on
the premise that the uplink frequency is 10 kHz below what was originally
published. That worked again tonight. I used narrow FM on the uplink radio,
and narrowed the receive bandwidth and adjusted the audio filtering in
HDSDR so I wouldn't hear any buzzing or other noises from the telemetry on
the downlink. Normally HDSDR's AFC works very well with AO-85's downlink,
but for several minutes the AFC kept sliding my receive frequency down to
the XW-2F CW beacon just below the AO-85 downlink. I had to turn off the
AFC until the two signals had more separation between them. Once the XW-2F
CW beacon went lower in frequency, away from the AO-85 downlink, I resumed
using AFC. I had no AFC-related problems for the remainder of the pass.

The nominal frequency of the AO-85 downlink seemed to be closer to 145.978
MHz tonight. This may complicate working this satellite for some, who may
not want to adjust the downlink frequency. The Chinese-made HTs I have used
would definitely need to have the downlink frequency adjusted during AO-85
passes. Some non-Chinese radios may be able to start passes on 145.980 MHz,
but have to be adjusted down to 145.975 MHz for the last part of the pass.
This may not be a hard-and-fast rule for all non-Chinese radios, depending
on how sharp or forgiving the front-end filtering happens to be on these
radios. When I worked earlier AO-85 passes with the Wouxun HTs, and the
Icom IC-2820H last night, I just use the VFOs. No memory channels. I set
both VFOs for narrow FM, set the 67.0 Hz CTCSS tone in the transmit VFO,
5 kHz tuning step in the transmit VFO, and the smallest possible FM tuning
step in the receive VFO (5 kHz for the IC-2820H, 2.5 kHz for the Wouxun

Since I was not home for these passes, I did not try a different radio (or
radio combination) for AO-85. If time permits in the next couple of days,
and if the transponder is on in the evenings for western US passes, I might
be able to try another radio or two before leaving for the AMSAT Symposium.
Otherwise, trying different radios on AO-85 will resume after I return from
Dayton, later this month.

Again, thanks to AMSAT for making the AO-85 transponder available over this
weekend! It has been fun to work a satellite that's only been in orbit now
for just over 3 days. I hope the telemetry and other tests are showing the
satellite in good working order. And thanks to all of the stations that
called or worked WD9EWK during this afternoon and early evening. :-)


Twitter: @WD9EWK

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